Adventure time with Jack: into the nightosphere
by jaketheripper
Summary: i appologize for the lack of updates, I'm sort of going through some family turmoil. thank you for being patient
1. Chapter 1

**Adventure Time with Jack**

**into the nightosphere**

**by Jaketheripper**

"NO HUNSON! WHAT ARE YOU DOING?!"

the wide set man was toying with The enchirideon, but he had gone too far this time!

"I'm unlocking the secrets to immortality!"

"YOU'VE GONE MAD!"

"have I? Mr. old magic can solve new problems?"

"STOP!"

little jack walked into the room, his father was shouting through the glass at uncle hunson, the glow from the enchirideon casting a green glow on the man's face, "daddy?"

"go back to simon, Jack, i've got to teach hunson a lesson."

and with that, Jack's father seized an axe and began to hack at the door to Hunson's lab.

Jack woke up and screamed in pain, he looked at his body, it was enveloped in blackness, he looked up and saw Hunson Abadeer staring him in the face, " rise and shine little Jackson, rise, and, shine..."


	2. Chapter 2

Jack struggled, "what am i doing here? what are you doing to me?"

Hunson cackled, "oh please, don't be so melodramatic, I'm healing you, my Daughter took you here, you are dead, true, but so am i."

he let Jack go, Jack fell to the cold stone floor, he got up and looked at himself in the large mirror next to his bed, he had grey skin and pointy ears, his teeth were sharp and pointy, "no...NO!"

"oh yes, my little nephew, you are now one of us."

he fell to his knees, "this can't be..."

"i felt your father die only minutes before you arrived, is the great lich finally dead?"

"my father died when he became the lich, all that was left was a lust for destruction, YOU HAVE NO RIGHT TO SOIL HIS NAME!"

with that, Jack turned and struck at Abadeer, raking claws up the old demon's face, he staggered back with a roar of pain, "GAARRRGGHHH!"

Jack stood there and looked at his claw, the large sickle shaped blades protruding from his hand, he snarled, "i'm going to kill you for taking away my chance of being with my wife again."

with that his body generated armor, his other hand grew a claw as well, Abadeed straightened up, "i can see you've already gotten the hang of your powers."

"DIE!" Jack charged at Abadeer, slashing with his claws, hunson dodged the first five strikes but then on the sixth pass he was hit in the eye, the rest was bloody and ugly, till Abadeer lay splaid on the floor, bleeding from everywhere, but still laughing, "you can't kill me, I sired you."

"but that doesn't mean i can't make it hurt like hell."

he raised his claw, but then heard a shout, "NO!"

he looked up to see Marceline running to him, she flung her arms around him and hugged him tightly, "please...no more...just stop...change back...please jack, im begging you."

taken aback, his armor receded, the claws shrunk and he hugged the crying marceline, "I thought he wouldnt be able to save you."

Abadeer sat up, already healing, "always the best for you, sweetheart."

Jack roared at the sight, "IM NEVER GOING TO BE ABLE TO WALK IN THE SUN BECAUSE OF YOU!"

struggling against a still tearful marceline, he eventually grew tired.

"please Jack, just wait...I'm sorry for this but...i couldnt loose you..."

Jack stopped and looked down at marcy, who had buried her face in his chest, "please...just stop..."

he sat down and hugged her back earnestly this time as abadeer melded through the wall.

"I'm sorry Marcy, I don't know what came over me."

she sobbed, "you...you were dead..."

"i know."

"but now you'll be with me forever, I...i love you Jack...I'm so sorry for everything...please...forgive me..."

he stroked her raven hair, smilng a bit in spite of himself, "no, I'm sorry marceline, I over reacted, I'm very glad you helped me, now i can watch my son and daughter grow up."

she cuddled him and he held her close, "I never want to loose you ever again..."

these words triggered a memory, one that he barely remembered, and one he was sure marcy had long forgotten, it was two years before the war, he was sitting in the lab with his father when he heard some girl crying in the hall, he walked out to see a little girl with pale skin and black hair sitting in the hallway cryin her eyes out, he walked up and poked her, "what's wrong?"

"i-i-i-i can't find my daddy!"

Jack stopped to think for a moment, "is his name hunson?"

she looked up, "yea, why?"

"because my dad works with him, follow me."

with that they walked down the hallway to Hunson's lab, he was poking something that looked like a demonic slug with a probe, he looked up and smiled, "oh!"

he ran to them and picked up little marcy, "oh Marcy, did you get lost again?"

"mmhmm."

"well, i'm glad jack helped you get back."

"can we get icecream soon?"

"as soon as i'm done studying."

with that, Marceline sat down and watched him dissect whatever it was, Jack piped up as they were about to leave, "uncle hunson, where's simon? did he get fired?"

"oh, no Jack, he was sent on an archeological expidition to the antarctic, some powerful elemental magic up there, he'll be back in a week or so."

and with that, his memory fades into his others, he had only just realized that they had met that long ago.

"Jack?"

he looked down at Marcy, "yes?"

"are you ok?"

"im fine."

"good, because we've got to get you back to ooo before my dad gets any ideas."

Jack got up, "my coat? sword? hat?"

"all in here."

she opened a chest and pulled them out, Jack put them on.

"alright then, let's get the fuck out of the nightoshere."


	3. Chapter 3

Finn held Bonnibel and watched the portal from his room window, "they've been gone a while..." he managed

Bonnibel hugged him, "it's going to be fine, she'll get jack back here, Marceline wouldnt let you down like that would she?"

"no...i guess not..."

"that's the spirit, now how about we go downstairs and join the others?"

"ok..."

with this, they walked down to the lower level where fionna, Jake, prince gumball, ice king and Billy were making dinner, Finn raised an eyebrow, "what. are. you. doing?"

Fionna looked up at Finn, "oh, we're just making a proper dinner."

"can i help?"

"no."

"why not?"

"because boys cook, only a woman can create quisine!" with the last word she made a grand gesture out in front of her and her eyes shone with delight, Finn sighed, "ok."

he sat down on the couch with bonnibel and laid back, he was drifting off to sleep when suddenly there was a knock at the door.

jake's arm extended and opened the door to reveal Jack with a more wide brimmed hat than before, his face hidden in shadow, Marceline holding him up, "OHMYGLOB!" finn lept up and Bonnibel smiled, "told ya, finn!"

Marcy helped jack sit down, he groaned, Finn ran up to him just as he took off his hat, Finn came to a stop, "AAH!"

Jack gentured frantically, "finn, finn, calm down it's me."

"...dad?"

Fionna saw what he had become and dropped her knife, "oh...no..."

Jack sighed and closed his eyes, "it's going to be alright, this is what i had to become in order to come home to see you all again."

finn hugged him, "you're...cold.."

"i know, i'm a vampire now, like marcy."

Marceline held up a thumbs up, "he's ok, he's still your dad, no matter how weird he looks."

Finn nodded, Fionna ran up and hugged him too, he smiled, "you guys are all i have, I could never desert you like that."

Fionna sighed, "dad-" jack interrupted, "something's burning."

"ohglob! the potatoes!"

she immediatley ran back into the kitchen, much to the humor of Jack, who stretched, "well, i'm so ready for dinner."

"good! because we made it especially for you."

Jack walked up to ice king, "simon, oh. my. glob. you look so OLD!"

"says you, Jack, i don't understand how you survived the war or the 10000 years proceeding it, being human the whole time."

Jack smiled, "i did a favor for a certain Demigod, he put in a good word with his father, i was immortal for the duration of the war."

"cheater."

"oh shudap."

"so Dad, what do we do now?"

Jack frowned, he was at a loss for what to do, "well...I'm wondering something about Fionna..."

Marceline looked, "oh, Jack, no..."

"there's no no about this no, I need to find out how and why marshall did this to her."

"so what are you going to do?"

Jack got up, "come along Marcy, we're going to see your brother's grave."

and with that, he put on his coat and hat and walked out the door, followed in short, by Marceline with her sun hat.


	4. Chapter 4

"why do you insist on going to marshall's grave?"

Jack growled, "because, Marshall did horrible things to my daughter, it's time to make him feel the pain he caused."

"he's DEAD! i think he's experiencing plenty of pain where he is now."

Jack drew a smiley face in the ground, "no, no Jack what are you doing?"

she tried to stop him but he gently pushed her away, "if you're right, then he's in the nightosphere, he's going to pay for what he did."

he pulled a warm carton of bug milk from his coat, as he raised his hand, Marceline caught his hand, "NO!"

"why not?"

"because father will destroy you."

"abadeer isn't my concern, let go marcy."

she was in tears, she saw this was futile but she was resolved to not let him go.

"no."

his face morphed into a troll face as he tipped his wrist and the bug milk splashed on to the happy face, " _Dominus vobiscum/Pax vobis. Et cum spiritu tuo_"

the portal opened and he picked marceline up, "HEY!"

he jumped through the portal and set her down, they looked around, he saw marshall before she did, he flew at him, roaring, "MARSHALL!"

marshall turned to see him, he panicked and flew the opposite direction, but he was caught and shaken by Jack, who laughed ominously, "you're coming with me."

Marshall saw the flames reflected in Jack's eyes, "w-what are you going to do?"

"i'm not going to kill you and spoil the fun if that's what you're wondering."

and with that, Jack and Marceline flew back out of the portal, accompanied by Marshall.


	5. Chapter 5

"why are you doing this?"

"why did you RAPE MY DAUGHTER?!"

Jack puled the shades up again and let the sunlight sear Marshall's flesh, he screamed and Jack put the shades back down, "why, Marshall?" asked marceline, who was sitting in the corner opposite her brother, she was crying, "why did you do it?"

"BECAUSE I DIDN'T WANT TO SHARE HER!"

there was silence, marceline was the first one to speak, "what?"

"she was always so god damn lovey dovey with prince gum wad! She only laughed when I flirted with her, she didn't even think of me as an option! Why the fuck do you think I did that to her?" He began to cry, "she was the only one I could willingly get to spend time with me."

Jack raked claws across Marshall's face, "don't start sparkling on me now, Edward!"

"...who?"

"Nevermind, jus stop being so damn emo!"

Marceline laughed as Jack turned back to Marshall, "what all did you do to her? And how many times was it RIGHT UNDER MY NOSE?!"

as he said this he impaled his sword through Marshall's junk, stabbing through the chair into the floor, he screamed as black blood seeped over the chair and on to the floor down his sword.

Marceline left the room, in tears.

Marshall shuddered and sobbed a bit more before he was able to look back up at Jack, "at least 8 times..."

"you've got balls marshall, or at least you had balls."

he twisted the sword and Marshall screamed again as another torrent of black blood deluged down the sword onto the floor.

"it's because of your dumbassery with the lich that I'm like this."

"L-like what?"

Jack took off his hat and revealed his black hair, gray skin and pointy ears, "you need to pay more attention, your father turned me into one of YOU!" He stabbed a silver kunai into marshall's shoulder, twisting the sword more, Marshall sobbed some more, "you would do that' wouldn't you?"

"do what?"

"cry like a BITCH!" Jack plunged his hands through Marshall's ribcage and wrapped around his heart, Marshall choked as he felt his lungs move aside, he looked up at Jack, "does this make you happy? To torture me?"

"y'know what? Yes, yes it does."

"I don't think this is your fatherly protection anymore, you're giving in, welcome to the dark side pops."

"SHUT UP! YOU RAPED MY DAUGHTER!"

"THEN FINISH ME!"

"NO!"

they both look around to see fionna standing there with marceline.

"Fionna..."

"sweetheart, go back downstairs, daddy's busy."

"dad, stop! He's had enough!"

"no fionna, let him do it, I want to see if he'll go through with it." Marshall looked defiantly into Jack's eyes, "no, dad, please!"

"Fionna...this...THING...did things to you...things I can never prevent, but things I can AVENGE!"

he squeezed a bit on Marshall's Heart, he gasped but Jack stopped again when fionna interrupted, "dad, I know...Marceline told me."

Jack smiled a jagged and serrated smile, "then you know why I'm doing this!"

"no dad, I don't."

Jack relaxed his grip, "what?"

"I mean, i get the intent, but he was dead already, I think you're doing this to make yourself feel better, but now he's here and sane, he can appologize, and you can back off, please."

Jack looked snarlingly at Marshall, "I'm not done with you yet."

with that, he removed his hand, the kunai and the sword, he put his hat back on and pushed past the others as he stormed downstairs and out the front door, into the night.

Fionna ran to Marshall, "oh man..."


	6. Chapter 6

***morpheus face* what if i told you that riding my ass for an update, doesn't make me write faster?**

**as punishment i shall only give you HALF A CHAPTER!**

Marshall couldn't move, Fionna ran to him, "marshall, oh man..."

"fuh...fionna..."

she sighed, "I wanted to do this to you too at first but...i guess i'm more forgiving than my dad..."

Marceline floated towards the two, "fionna..."

"i know, Marceline, i know he's dangerous."

"i...fionna...i..."

"you what?"

"i love...i..."

Marceline growled, "you don't know what love IS!"

suddenly there was a shattering sound, the door flew off it's hinges and a demon strode through the doors, "return marshall lee to his father!"

Fionna drew her sword and Marceline's lich armor appeared again, "who are you?"

the dempn soldier drew his greatsword, "I AM ADVENT! I AM YOUR HALF BROTHER! NOW STEP ASIDE OR YOU WILL BE DESTROYED!"

Marceline got in his face, "you think you can threaten me? you think i'm affraid of you? well you're wrong."

Advent backed up against the wall as she advanced on him, "BACK UP! I'LL KILL YOU!"

Marceline chuckled, "i doubt you even know how to use that sword."

Advent roared and charged, swinging the greatsword wildly, "DIE!"

he was tossed out the window by Marcy.

"well...that's over..."


	7. Chapter 7

**ok, now that i'm done raging you can have the other half, then i commense with the whole chapterness.**

Jack walked across a field, his eyes glowing red as he snarled at the grass and the moon, suddenly as he looked at the moon he stopped to think.

"...cesily...I have failed you." he fell to his knees, looking up at the moon, remembering how she was always with him, like the moon, forever dogging him, tears came to his eyes as he remembered how she had been taken, how the magic man had laughed, how he had laughed and taunted him as he teleported away.

"why weren't you with finn? where did he take you?"

there was a familiar laugh, something that sent tingles of rage down his spine, his eyes glowed red again, "because she didn't WANT to wait for you."

Jack stood and turned to see the green skinned man in the yellow hat laughing and pointing at him in obvious delight, "my, my, my Jack, how long has it been? it seems at least 20 years since we last met."

"where is she?"

"oh like i'd ever tell you."

"RRRAAAGH!" Jack grabbed him by the shirt and immediatley draped his trench coat around the man's shoulders, the magic man tried to teleport away but nothing happened, "what?"

Jack grinned his shark tooth smile, "magic proof coat, magic man, that means you're mine."

with this, Jack tore into the magic man, shredding his flesh with his claws and teeth as the martian screamed in agony and pain.

when he was satisfied, Jack strung magic man up on a tree by his hamstrings, he was crying, screaming in pain as his body bobbed up and down, "so, MARTIAN, tell me, WHERE IS MY WIFE?!" he tugged hard on magic man and the strings strained, he screamed, "AAAAAAAAIIIAAAAGGGHHHHHHHHHH !"

"well? i'm waiting."

"she...she died two years ago..." a photo fell out of magic man's pocket and Jack picked it up, "no...NO!" it was a picture of cesily, a beautiful blonde princess, standing next to magic man with a wedding dress on, she looked happy, Jack turned to Magic man furiously, "YOU!"

Magic man whimpered and peed himself as he saw Jack grow and mutate until he stood as a monster with thousands of eyes and billions of tentacles, "YOU'RE SUFFERING WILL BE ENDLESS!"

eight hours of torture later, however, Magic man died of bloodloss and shock, finally.

Jack sighed as he turned back into a humanoid vampire, he looked at the picture again, he looked back down at the smile on her face, "at...at least you were...happy..."

he fell to his knees and began to sob.

**back at the treehouse**

the door had been barriccaded, a demonic army was standing outside, "RETURN MARSHALL!" "RETURN MARSHALL!"

Finn and Ice King were waiting with Billy and Jake for them to break the door down, finn looked at Billy, "what do we do?"

Billy smiled, "they cannot come in unless invited."

Ice king looked up at billy, "really?"

Billy nodded confidently and they all lowered their weapons, "huh.."

suddenly the door broke down and in ran Advent again, "KILL THEM ALL!"

the demons charged in and the fighting began.


	8. Chapter 8

Marceline heard and rushed downstairs to aid Finn, jake, ice king, gumball and billy.

Fionna, taking advantage of the abcense of Marshall's sister, hugged him, "she still doesn't know ..."

"oh thank glob, I was affraid for a minute there that I had lost you, fionna."

"They wouldn't understand...they can never know...Gumball...I don't think he'll tell either..."

"he'd better not."

"dad fucked you up pretty bad."

"I understand his position, after all we did...why did you want me to enslave you again?"

"because I had no sexual experience a the time..."

"and that's changed?"

"ever since that time you and gumball double teamed me in the royal bedroom, I consider myself experienced."

"I'm surprised you didn't get prego from that."

Fionna giggled, "neither of you are human."

"some less than others."

"Just because he's bigger than you doesn't mean you can ridicule him."

"bu-fine...can you get me out of here?"

"only if you take me with you."

"what about gumball?"

"he's a prince, he'll be fine."

as Fionna untied him, his wounds healed and Fionna kissed him deeply, her nipples hardening as she remembered everything, she felt her panties flood again as he flew out the window Carrying her with him into the night.

Jack ran to his house to see the army, he roared his challenge and drew his sword as he ran at the demon army, "AAAAAAAAAArRRRRRhHHHH!"

and like a great tide of evil they turned from the house and charged at the lone warrior, crashing Into him and raging over him, burying him as the vampire human couple flew away under cover of darkness.


	9. Chapter 9

**sorry for my lateness, I only have half done, but its good.**

Fionna smiled as Marshall set her down in his castle, "I feel kinda bad for leaving everyone."

Marshall chuckled, "they'll be fine."

she looked around, "looks darker than last time I was here.

Marshall laughed, "it always gets this way at night.

he flies around her, smiling a he circles closer and closer to her, taking her in, savoring the way she looked, for that would soon change.

"my sister, as you know, has gone full good guy, so..." he floated closer and curled around her like a snake, he liked her lobe as he whispered into her ear, "the vampires are in need of a new queen..."

The whisper, combined with the lick, sent shivers down Fiona's spine, she felt her panties flood again as she realized what he was saying, "hhhh.."

he smiled, Marceline had removed the brainwashing effects of his bite, but she was still his to command and take at will.

"so...wanna be a vampire?" He asked, slipping a hand under her dress to plunge into her panties, the other massaging her left breast.

Fionna whimpered, she felt three fingers plunge into her sopping pussy as a thumb entered her ass, "y-yes...oh glob yes..." she arched her back and kissed him, he had her, body and soul.

suddenly his teeth grew and they plunged into her neck, she moaned as she felt the vampire's venom snake into her veins, and like that, everything went black.

Fionna woke in a bed, she looked around, Marshall wasn't there, she got up and looked around for him, "Marshall?"

suddenly she stopped and turned, there in a mirror was nothing, she couldn't see herself.

"OH GLOB!"


End file.
